[evlatests] Some more curious phenomena

[Rick Perley]

    Some more curiosities -- all of a minor nature -- seen in the test 
data taken Monday afternoon at C-band.

    A) As noted by Vivek, the cross-power amplitudes don't change 
between sub-band widths.  This is a good thing. 

    B) The variation in cross-power amplitudes between antennas, in IFs 
B and D, can be rather large.  This is presumably the result of using a 
table to set the T304 attenuators, rather than adjusting by the power 
measured by the TPDs.  The maximum variation seen in IFs B and D is 
nearly 6 dB (a factor of four in power, or two in amplitude).  The 
antenna-IFs which are furthest from the average are:  1B, 16B, 17B 28B 
and 23D, all of which are a factor of two away from the average in power. 

    C) The cross-power variation between antennas in IFs A and C is very 
much less -- as expected.  However, antenna 28 is an exception:  28A is 
high by about 1.5 dB, and 28C is low by nearly 3dB. 

    D) Antenna 28, if IFs A and B (RCP) has a large (1dB in power) 
ripple in the bandpass, of 40 MHz period -- corresponding to a 3.75 
meter resonance.  All antennas show some ripple, but this one stands out.